Rotating flat specimen device for the geiger counter x-ray spectrometer



April 1, 1958 K. LOWITZSCH ET AL 2,829,251

ROTATING FLAT SPECIMEN DEVICE FOR'THE GEIGER COUNTER X-RAY SPECTROMETERFiled Dec. 31, 1953 3 Sheets-Sheet l I INVENTORS. K ugrllownsoz ByMLLIAM Pmanbsn AGENT.

April 1, 1953 K. LowlTzscH ET AL 2,829,261

ROTATING FLAT SPECIMEN DEVICE FOR THE GEIGER COUNTER X-RAY SPECTROMETER-Filed Dec. 31, 1953 3 Sheets-Sheet 2 IN V EN TORS. KURT LowIrscH BYMLLIAMPARRZSH AGENT.

2,829,261 EIGER 'April 1,- 1958 K. LOWITZSCH ET AL ROTATING FLATSPECIMEN DEVICE FOR THE G COUNTER X-RAY SPECTROMETER '3 Sheets-Sheet 3Filed Dec. 31. 1953 IN VEN TORS. KURT LOWIT/SCH y WILLIAM PARRLSJI fi/WAGENT.

23293261 Patented Apr. 1, 1958 fine ROTATING FLAT SPECEMEN DEVICE FORTHE GEIGER COUNTER X-RAY SPECTROME'I'ER Kurt Lowitzsch, Yonkers, andWilliam Parrish, Hastings,

N. Y., assignors, by mesneassignments, to North American PhilipsCompany, Inc., New York, N. Y., a corporation of Delaware ApplicationDecember 31, 1953, Serial No. 401,520 3 Claims. v(Cl. 250-51) Thisinvention relates to a rotating fiat specimen holder for use with aGeiger counter X-ray spectrometer. 1

It is an object of the present invention to provide a rotating flatspecimen holder which when properly aligned results in accurate relativeintensity measurements. The present rotating flat specimen holderincorporates builtin grooves or slits which permit the specimen holderand its cooperating elements to 'be adjusted without the use ofadditional fixtures.

Here'tofore, the stationary sample holder used in a Geiger counter X-rayspectrometer showed extremely large statistical variations of theparticles of the powder sample or specimen. These statistical variationsmay be reduced by using much smaller particle sizes but even when theparticles are reduced to less than 10g the statistical variations of thespecimen or sample are still excessive.

It is an object of the present invention to obviate the aforesaiddifliculties by providing a flat specimen holder which is designed torotate at a moderate speed preferably around 77 R. P. M around an axisperpendicular ot the irradiated surface. This rotational movement isnecessary in order to obtain accurate relative intensity measurements.

A further object of the present invention is to provide a rotating fiatspecimen device which gives accurate and reproducible results and aconsiderable gain over the conventional stationary sample holder.

Another object of the present invention is to provide a rotating flatspecimen holder which can be incorporated in the X-ray unit without anyadditional fixtures and when once aligned with respect to the X-ray beamremains aligned. Thus, the present holder may be taken out of the unitand placed back in again after the initial alignment withoutnecessitating an additional alignment thereof.

The above and other features, objects and advantages of the presentinvention will be fully understood from the following descriptionconsidered in connection with the accompanying illustrative drawings.

Fig. 1 is a perspective View of the rotating flat specimen deviceembodying the present invention showing an exploded view of the specimenholder and retainer unit,

Fig. 2 is a fragmentary perspective view of the rotating fiat specimendevice in position with an X-ray source and a Geiger counter tube inoperating condition,

Fig. 3 is a sectional view taken along the lines 33 of Fig. 1,

Fig. 4 is a side elevation view of the front end of the rotating flatspecimen device partially in section,

Fig. 5 is a front elevation view of the alignment fixtures of the deviceembodying the present invention,

Fig. 6 is a top plan view thereof,

Fig. 7 is a rear elevation view thereof.

It is to be noted that the X-ray diffraction goniometer utilized withthe present invention may be aligned for the zero degree 0 position ofthe specimen surface which must be precisely one-half the angle of 26,the angular position of the Geiger tube, Where 0 is the Bragg angle forX-ray diffraction in accordance with known procedures and form no partof the present invention.

In order to accomplish the foregoing procedure, the present rotatingflat specimen holder device as shown in Figs. 1-4 is inserted throughthe same aperture that an alignment gauge (not shown) had previouslyutilized in order to set the Geiger tube position to 0 20.

Referring now more particulary to Fig. 1 wherein the rotating flatspecimen device embodying the present invention is shown motivated by adriving unit 10. The rotating specimen device itself is mounted so thatan X-ray tube enclosed in X-ray source 12 projects a beam which isreflected or radiated from the atomic planes of the elements of thespecimen powder sample A to a Geiger counter tube 14 for translation ofthe information received therefrom (see Fig. 2). It is to be understoodthat the X-ray source, Geiger counter tube, and driving unit form nopart of the present invention, the invention being directed to themethod for aligning the rotating flat specimen device on an X-raydiffraction goniometer and a device for accomplishing the same in orderto obtain accurate relative intensity measurements.

The rotating flat specimen device is provided with a rotating shaft 16enclosed in a sleeve 62, said shaft 16 being motivated by driving unit10. At one end of rotating shaft 16 a gear 18 is located, said gearbeing adapted to mesh with a spur gear in driving unit it (not shown).It should be apparent that the aforesaid spur gear by means of drivingunit 10 imparts movement to rotating shaft 16. Gear 20 at the other endof rotating shaft 16 meshes with gear 22 of rotating sleeve or ring 24to form a bevel gear arrangement. A mounting assembly 26 for rotatingsleeve '24 comprises a cylindrical integral element 28 which serves as asupport for a cylindrical hood or shield (not shown) which is adapted tofit thereover and to thereby confine X-ray radiation within a narrowpath from the X-ray tube to the Geiger counter tube. 7

Mounting assembly 26 further comprises a horizontal bracket 30 whichserves as a mounting for the rotating sleeve 24. Rotating sleeve 24 isfurther provided with a ground ring 32 which projects above the topsurface 34 of the horizontal bracket. The top surface 34 is machinedprecisely to be co-extensive with the longitudinal axis 36 of therotatingshaft 16. Specimen holdor 38 is adapted to fit, in retainer 40thereby forming a combined unit. This combined unit may be inserted inthe bore of a rotating sleeve 24 (see Fig. l). The aforesaid combinedunit is preferably held in position by means of bayonet pins 42 whichproject laterally from retainer 40 and which are adapted to be removablyinserted in the bayonet slots 44 in the bottom side walls of rotatingsleeve 24. It is to be understood that we do not intend to necessarilylimit ourselves to the aforesaid method of securing specimen holder 38in the bore of rotating sleeve 24 but that other suitable means may beemployed to accomplish this purpose.

A groove 46 is preferably cut .001 inch in the top surface 34 at twoaligned, opposite places while corresponding grooves 48 are cut .001inch in the ground ring 32 of rotating sleeve 24.

Surrounding the shaft 16 is an arm 50 integral with cylindrical element28 and a collar 52 which constitute an alignment fixture for the device.This arm and collar have a plurality of screws 54, 56 and 58 thereinwhich are manipulated together with a screw 60 in cylindrical element 28in order to translate the rotating fiat specimen device in a horizontalplane and also to rock the device around its axis of rotation. As seenin Fig. 6

the collar 52 is of the shape illustrated having a U-shaped top portionprovided with a relatively thick leg 53 and a relatively thin leg 51.The screw 54 moves the thinner leg 51 toward thicker leg 53 therebyfixing the collar 52 to the locating pin 19 ,(Figs. 5 and 5a) of thegoniometer. Figs. 5 and 5a, illustrate the arm 50 which is integral withmounting assembly 26. Since collar 52 is fixed the rotation of screw 56will cause both arm 50 and the mounting assembly to rock about the axisof rotation of the specimen holder 38.

The present device may be aligned by performing the following steps:Rotate ground ring 32 in its own plane untilgroove 48 coincides withgroove 46 of the horizontal bracket 30. The depth positioning of thedevice should then be checked to make certain that the center of groove46 is in line with the center of the slits of the X-ray source. This isaccomplished by translating the device in the horizontal plane byadjusting screw 60 that bears against goniometer fixture17 which isfixed to the goniometer (Figs. 2 and 5a). The screw 54 is then tightenedthereby causing the thinner leg 51 of collar 52 to move into clampingengagement with locating pin 19 of the goniometer assembly. Thus, thecollar 52 is rigidly fixed to the goniometer through locating pin 19..Screw S8 is then loosened and screw 56 is adjusted to cause rocking" orangular rotation of the mounting assembly 26 since arm 50 is integralwith mounting assembly 26 and collar 52 will not move since it isrigidly fixed to the goniometer. The groove 46 is caused to rock untilthe slot is precisely aligned to the 0 X-ray beam. This position of theX-ray beam is located by external instruments which measurethehighestintensity of X-ray beam projected through the grooves 46 and48. When the foregoing is accomplished the mounting surface of therotating fiat specimen is set automatically for the angle 0.

' Finally, screw 58 is tightened in. order to permanently position therotating fiat specimen device in relation to the X-ray source and theGeiger counter tube position. It should be noted that it is within thescope of the present invention to provide only a single, groove or slitas an alignment means for the 2:1 setting of the goniometer.

While we have shown and described the preferred embodimentof ourinvention, it will be understood that the latter may be embodiedotherwise than as herein specifically illustrated or described and thatin the illustrated embodiment certain changesin the details ofconstruction and in the arrangement of parts may be made withoutdeparting from the underlying idea or principle of the invention withinthe scope of the appended claims.

What we claim is:

l. A rotating flat specimen device for use in X-ray analysis comprisinga driving means, a sleeve member secured at one end to said drivingmeans and being provided at its other end with an enlarged suportingelement positioned co-axially with said sleeve member, a rotating shaftin said sleeve member operatively connected to said driving means, ahorizontal bracket fixed to said supporting element, a rotatable sleevemounted in said horizontal bracket and operatively connected to saidrotating shaft, said rotatable sleeve being provided with a ring havingat least one surface thereof projecting above the plane of the topsurface of said horizontal bracket, said ring having a pair of aligned,opposed grooves therein for the passage of X-ray beams therethrough, aspecimen holder, and means mounting said specimen holder in saidrotatable ring.

2. A rotating flat specimen device for use in X-ray analysis comprisinga driving means, a sleeve member secured to said driving means at oneend thereof and being provided with a supporting element at the otherend thereof, a rotating shaft in said sleeve member operativelyconnected to said driving means, a horizontal bracket fixed to saidsupporting element, a rotatable ring mounted in said horizontal bracketand operatively connected to said rotating shaft, a specimen holdermounted in said rotatable ring and an arm and collar member adjacent toeach other, and means co-acting with said arm and collar member forpermitting limited angular rotational movement of said horizontalbracket.

3. A rotating flat specimendevice for use in X-ray analysis comprising adriving means, a sleeve member secured at one end to said driving meansand being provided at its other end with an enlarged supporting elementpositioned co-axially with said sleeve member, a rotating shaft in saidsleeve member operatively connected to said driving means, a horizontalbracket fixed to said supporting element, a rotatable sleeve mounted insaid horizontal bracket and operatively connected to said rotatingshaft, said rotatable sleeve being provided with a ring having at leastone surface thereof projecting above the plane of the top surface ofsaid horizontal bracket, said ring and the top surface of saidhorizontal bracket eachhaving a pair of aligned, opposed grooves,therein for the passage of X-ray beams therethrough, a specimen holder,and means mounting said specimenholder insaid rotatable ring.

References Cited in the file of this patent UNITED STATES PATENTS2,490,673 Champaygne et al Dec. 6, 1949 2,500,926 Boyd Mar.21, 19502,500,948 Kaiser et al Mar. 21, 1950 2,585,740 Claassen Feb. 12, 19522,602,899 Page July 8, 1952 2,626,359 Weber Jan. 20, 1953

